mission in benghazi in libya, which killed ambassador chris stevens and three other americans. >>> encouraging developments in the fight against leukemia. this is p happening at the university of pennsylvania where doctors are using gene therapy to eradicate certain types of blood cancers. this is done using the patient's immune system t-cells to personalize treatments. in cases involving terminally ill patients, three of them are now free of the disease. the findings considered very preliminary are already being presented by penn's research team. >>> secondary assault charges filed against two university of colorado boulder students accused of bringing marijuana laced brownies to class. five classmates and their unsuspecting professor were sickened when they ate the brownies. the two students are behind bars and facing possible jail time. last month colorado voters approved the recreational use and possession of small amounts of marijuana. >>> so since friday morning, people in houston have been talking about a strange fireball seen streaking through the morning sky. was it falling space junc